A08758 — CAN: Maximum number of valid PDO exceeded

A08758 is raised when an attempt is made to exceed the maximum number of valid PDO on the CAN interface. PDO means Process Data Object: an RPDO (Receive Process Data Object) is received by the drive, a TPDO (Transmit Process Data Object) is transmitted by it. The limit applies to the total number of valid PDO across all CANopen-supported drive objects, not to a single drive object. The alarm value in r2124 tells you which of the two limits was hit.

• An attempt was made to exceed the maximum number of valid PDO — on the receive side (RPDO) or on the transmit side (TPDO) of the CAN interface.
• For the RPDO the limit follows from the hardware: at most 25 valid RPDO are possible in total across all CANopen-supported drive objects.
• For the TPDO the limit results from the ratio of CAN sampling time (p8848) to CAN minimum processing time (r8739).

1. Read the alarm value in r2124, interpreting it decimal: value 1 means the RPDO limit was exceeded, value 2 the TPDO limit.
2. If the RPDO limit was exceeded, make the PDO configuration comply with the hardware limit of 25 valid RPDO in total across all CANopen-supported drive objects.
3. If the TPDO limit was exceeded, determine the permitted number of valid TPDO from the ratio of CAN sampling time (p8848) to CAN minimum processing time (r8739) and make the configuration comply with it.
4. Read r8742 to see how many RPDO or TPDO are still available.

• The drive stores the alarm value in r2124; interpret it decimal.
• 1: an attempt was made to exceed the total number of valid RPDO of all CANopen-supported drive objects. As a result of the hardware, the limit is 25 valid RPDO.
• 2: an attempt was made to exceed the total number of valid TPDO of all CANopen-supported drive objects. The limit is defined by the ratio: CAN sampling time (p8848) / CAN minimum processing time (r8739).

• r2124 — alarm value of this alarm; read it decimal to see whether the RPDO limit (1) or the TPDO limit (2) was exceeded.
• p8848 — CAN sampling time (listed in the parameter chapter as IF2 PZD sampling time); together with r8739 it defines how many valid TPDO are permitted.
• r8739 — CAN minimum processing time; together with p8848 it defines how many valid TPDO are permitted.
• r8742 — shows how many RPDO or TPDO remain available.
• p0009 — set to 30 for the warm restart that deletes the alarm.
• p0976 — set to 2 to execute the warm restart, together with p0009 = 30.

First make sure the number of valid RPDO or TPDO complies with the applicable limit. The alarm is then deleted by any one of the following actions: a successful write to the COB ID index of a PDO communication parameter (p870x[0], p872x[0]); a change of the CANopen NMT state; the CANopen NMT command reset node; the CANopen NMT command reset communication; a warm restart (p0009 = 30, p0976 = 2); or a POWER ON (switch-off/switch-on). No separate acknowledgement is required. r8742 indicates the remaining available RPDO or TPDO.